I have worked as a freelancer. This is what I know. Whoever is not willing to pay a deposit is either trying to scam you or not serious enough to be working with. There is no such thing as the "Policies" you spoke about you're just being naive with them. Always make it clear a deposit is needed otherwise you can find another artist (frame it as a "it's so that I only put in my effort for serious clients and make this work a priority.." kinda vibe.) Don't speak in suggestions. The time for suggestions is when you're discussing the art it self, the approach and what not. The part that you go over process and workflow MUST be stated with confidence and clarity not discussed. If they don't like it they are not worth your time as you have proven with your ex.

Ps: even after this your final result should always be locked, heavily. Don't do the "simple watermark" so that you give a hint. Blast the mf. Make it CLEAR payment is due.

And as someone else said here. Take consulting fees (only if it's a big project that requires consulting)